How to turn particles in circular shape
What you need to do is shift+a go-to curve/circle. Then add an object to the scene.
give that object a particle system and leave it all at default other than the object



then select the circle and go-to Physics and add forcefield



change the type to curve guide



you should be good! If you assigned the object with the particle system to itself you just need to duplicate it. Moving the particle emitting object will change the orbit size around the circle.

This is what it looks like (as a png sequence)